/*
 * Tencent is pleased to support the open source community by making Angel available.
 * 
 * Copyright (C) 2017 THL A29 Limited, a Tencent company. All rights reserved.
 * 
 * Licensed under the BSD 3-Clause License (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * 
 * https://opensource.org/licenses/BSD-3-Clause
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.tencent.angel.worker.storage;

import java.io.IOException;

/**
 * The interface Reader.
 *
 * @param <K> the KEY type
 * @param <V> the VALUE type
 */
// TODO: 17/6/29 by zmyer
public interface Reader<K, V> {

    /**
     * Read the next key, value pair
     *
     * @return true if a key/value pair was read
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    boolean nextKeyValue() throws IOException, InterruptedException;

    /**
     * Gets current key.
     *
     * @return the current key
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    K getCurrentKey() throws IOException, InterruptedException;

    /**
     * Gets current value.
     *
     * @return the current value
     * @throws IOException
     * @throws InterruptedException the interrupted exception
     */
    V getCurrentValue() throws IOException, InterruptedException;

    /**
     * Reset the Reader position to beginning
     *
     * @throws IOException
     */
    void reset() throws IOException;

    /**
     * Close.
     *
     * @throws IOException
     */
    void close() throws IOException;

    /**
     * Gets progress.
     *
     * @return the progress
     */
    float getProgress();
}
